hippydave,
I did a quick read of the 1955 2nd Series Truck Shop Manual
which you can read here on Page 4-66 concerning your carrier bearing question.
It really doesn't give a definition of how much movement is too much, just to clean and inspect the rubber cushion and replace if hardened, cracked, torn or badly distorted. On the bearing itself, it only says to check for broken balls and roughness. My best guess on the bearing is replace it if it shows signs of wear/roughness. It's supposed to be a sealed bearing so if you disassembly it, it must be replaced.
Will have to do some investigating on a source for replacement pieces. The parts books don't list a complete replacement "kit".
The actual bearing used is GM# 3760535 and I have seen NOS ones offered on eBay recently. The 1933-62 Chevy Parts Book indicates that is the correct bearing for 1955-59 1-1/2 ton trucks (as well as 1946-59 3/4 & 1 Ton trucks). The rubber cushion is also available NOS from many eBay sellers. Search for GM# 3730827 and you will find what you need.
Perhaps some fellow "Big Bolt" owners will chime in with some knowledge or sources for the parts besides what I found???
